Merge pull request #20 from snonux/develop

Make CGo dependencies optional (e.g. Linux ACL support)

23 files changed, 315 insertions, 162 deletions

diff --git a/.gitignore b/.gitignore
index 79c20cf..c9e8333 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,14 @@
 *_proprietary.go
+<<<<<<< HEAD
 cache/
 log/
+tags
+=======
+/cache/
+/log/
+/dtail
+/dgrep
+/dcat
+/dmap
+/dserver
+>>>>>>> 7ee0121afed3e7cab6457142f70e411020ab2b21
diff --git a/LICENSE.DataDog.zstd b/LICENSE.DataDog.zstd
new file mode 100644
index 0000000..345c1eb
--- /dev/null
+++ b/LICENSE.DataDog.zstd
@@ -0,0 +1,27 @@
+Simplified BSD License
+
+Copyright (c) 2016, Datadog <info@datadoghq.com>
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimer in the documentation
+      and/or other materials provided with the distribution.
+    * Neither the name of the copyright holder nor the names of its contributors
+      may be used to endorse or promote products derived from this software
+      without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/Makefile b/Makefile
index c8e5a12..6d85347 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,21 @@
 GO ?= go
 all: test build
 build:
+ifndef USE_ACL
 	${GO} build -o dserver ./cmd/dserver/main.go
+else
+	${GO} build -tags linuxacl -o dserver ./cmd/dserver/main.go
+endif
 	${GO} build -o dcat ./cmd/dcat/main.go
 	${GO} build -o dgrep ./cmd/dgrep/main.go
 	${GO} build -o dmap ./cmd/dmap/main.go
 	${GO} build -o dtail ./cmd/dtail/main.go
 install:
+ifndef USE_ACL
 	${GO} install ./cmd/dserver/main.go
+else
+	${GO} install -tags linuxacl ./cmd/dserver/main.go
+endif
 	${GO} install ./cmd/dcat/main.go
 	${GO} install ./cmd/dgrep/main.go
 	${GO} install ./cmd/dmap/main.go
@@ -17,7 +25,7 @@ clean:
 	  test -f $$cmd && rm $$cmd; \
 	done
 vet:
-	find . -type d | while read dir; do \
+	find . -type d | egrep -v '(./samples|./log|./doc)' | while read dir; do \
 	  echo ${GO} vet $$dir; \
 	  ${GO} vet $$dir; \
 	done
@@ -28,4 +36,8 @@ lint:
 	  golint $$dir; \
 	done
 test:
+ifndef USE_ACL
 	${GO} test ./... -v
+else
+	${GO} test -tags linuxacl ./... -v
+endif
diff --git a/README.md b/README.md
index 69d3153..d65d124 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ More
 
 * [How to contribute](CONTRIBUTING.md)
 * [Code of conduct](CODE_OF_CONDUCT.md)
-* [License](LICENSE)
+* [Licenses](doc/licenses.md)
 
 Credits
 =======
diff --git a/doc/drun.gif b/doc/drun.gif
deleted file mode 100644
index a3efeed..0000000
--- a/doc/drun.gif
+++ /dev/null
diff --git a/doc/installation.md b/doc/installation.md
index 6f946c4..6bf17b0 100644
--- a/doc/installation.md
+++ b/doc/installation.md
@@ -7,6 +7,26 @@ The following installation guide has been tested successfully on CentOS 7. You m
 
 Please check the [Quick Starting Guide](quickstart.md) for instructions how to compile DTail. It is recommended to automate the build process via your build pipeline (e.g. produce a deployable RPM via Jenkins). You don't have to use ``go get...`` to compile and install the binaries. You can also clone the repository and use ``make`` instead.
 
+## Linux ACL support
+
+This is optional but it gives you better security. On Linux you have the option to compile `dserver` with File System Access Control List support. For that you need:
+
+### 1. Install the `libacl` development library. On RHEL, CentOS and Fedora it would be
+
+```console
+% sudo dnf install libacl-devel -y
+```
+
+### 2. Enable ACL via a Go build flag
+
+Set the `USE_ACL` environment variable before invoking the make command.
+
+```console
+% export USE_ACL=yes
+```
+
+Alternatively you could just add `-tags linuxacl` to the Go compiler. 
+
 # Install it
 
 It is recommended to automate all the installation process outlined here. You could use a configuration management system such as Puppet, Chef or Ansible. However, that relies heavily on how your infrastructure is managed and is out of scope of this documentation.
diff --git a/doc/licenses.md b/doc/licenses.md
new file mode 100644
index 0000000..83a94e7
--- /dev/null
+++ b/doc/licenses.md
@@ -0,0 +1,11 @@
+Licenses
+========
+
+DTails main license is [Apache 2.0](../LICENSE). Further 3rd party licenses are:
+
+## DataDog zstd compression library
+
+Not included in DTail repository but imported automatically on build.
+
+* URL: https://github.com/DataDog/zstd
+* License: [Simplified BSD](../LICENSE.DataDog.zstd)
diff --git a/doc/quickstart.md b/doc/quickstart.md
index 6baedbb..f1ac000 100644
--- a/doc/quickstart.md
+++ b/doc/quickstart.md
@@ -7,12 +7,6 @@ This guide assumes that you know how to generate and configure a public/private
 
 # Install it
 
-On Linux you need to install the libacl development library for file system ACL permission support in `dserver`. On RHEL, CentOS and Fedora it would be
-
-```console
-% sudo dnf install libacl-devel -y
-```
-
 To compile and install all DTail binaries directly from GitHub run:
 
 ```console
diff --git a/docker/Dockerfile b/docker/Dockerfile
new file mode 100644
index 0000000..8632832
--- /dev/null
+++ b/docker/Dockerfile
@@ -0,0 +1,18 @@
+# This builds a container running DTail server
+# The container can be used for developing and testing
+# Purposes
+
+FROM fedora:33
+RUN mkdir -p /etc/dserver /var/run/dserver/ /var/log/dserver
+
+ADD ./dtail.json /etc/dserver/dtail.json
+ADD ./dserver /usr/local/bin/dserver
+
+RUN useradd dserver
+RUN chown -R dserver /var/run/dserver /var/log/dserver
+USER dserver
+
+WORKDIR /var/run/dserver
+EXPOSE 2222/tcp
+
+CMD ["/usr/local/bin/dserver", "-relaxedAuth", "-cfg", "/etc/dserver/dtail.json"]
diff --git a/docker/Makefile b/docker/Makefile
new file mode 100644
index 0000000..029adf6
--- /dev/null
+++ b/docker/Makefile
@@ -0,0 +1,10 @@
+all:
+	cp ../dserver .
+	docker build . -t dserver:develop
+	rm ./dserver
+run:
+	docker run -p 2222:2222 dserver:develop
+spinup:
+	./spinup.sh 10
+spindown:
+	./spindown.sh 10
diff --git a/docker/README.md b/docker/README.md
new file mode 100644
index 0000000..4d7e610
--- /dev/null
+++ b/docker/README.md
@@ -0,0 +1,5 @@
+# Docker
+
+The files in here are used for local development purposes only. E.g. you can
+build a dserver Docker container, create multiple instances of it and then
+mass connect to them via dtail client.
diff --git a/docker/dtail.json b/docker/dtail.json
new file mode 100644
index 0000000..d923101
--- /dev/null
+++ b/docker/dtail.json
@@ -0,0 +1,39 @@
+{
+  "Client": {},
+  "Server": {
+    "SSHBindAddress": "0.0.0.0",
+    "MaxConcurrentCats": 2,
+    "MaxConcurrentTails": 50,
+    "MaxConnections": 50,
+    "MapreduceLogFormat" : "default",
+    "HostKeyFile" : "cache/ssh_host_key",
+    "HostKeyBits" : 2048,
+    "Permissions": {
+      "Default": [
+        "readfiles:^/.*$",
+        "runcommands:^/.*$"
+      ],
+      "Users": {
+        "pbuetow": [
+          "readfiles:^/.*$",
+          "runcommands:^/.*$"
+        ],
+        "jblake": [
+          "readfiles:^/tmp/foo.log$",
+          "readfiles:^/.*$",
+          "readfiles:!^/tmp/bar.log$",
+          "runcommands:!^/.*$"
+        ]
+      }
+    }
+  },
+  "Common": {
+    "LogDir" : "/var/log/dserver",
+    "CacheDir" : "cache",
+    "TmpDir" : "tmp",
+    "LogStrategy": "daily",
+    "SSHPort": 2222,
+    "DebugEnable": true,
+    "ExperimentalFeaturesEnable": false
+  }
+}
diff --git a/docker/spindown.sh b/docker/spindown.sh
new file mode 100755
index 0000000..73ed059
--- /dev/null
+++ b/docker/spindown.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+
+declare -i NUM_INSTANCES=$1
+declare -i BASE_PORT=2222
+
+for (( i=0; i < $NUM_INSTANCES; i++ )); do
+    port=$[ BASE_PORT + i + 1 ]
+	docker stop dserver-serv$i 
+done
diff --git a/docker/spinup.sh b/docker/spinup.sh
new file mode 100755
index 0000000..3890ce6
--- /dev/null
+++ b/docker/spinup.sh
@@ -0,0 +1,9 @@
+#!/bin/bash
+
+declare -i NUM_INSTANCES=$1
+declare -i BASE_PORT=2222
+
+for (( i=0; i < $NUM_INSTANCES; i++ )); do
+    port=$[ BASE_PORT + i + 1 ]
+	docker run -d --name dserver-serv$i --hostname serv$i -p $port:2222 dserver:develop
+done
diff --git a/go.mod b/go.mod
index c19efe7..b52ed7a 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,8 @@ go 1.15
 
 require (
 	github.com/DataDog/zstd v1.4.5
+	github.com/google/go-licenses v0.0.0-20201026145851-73411c8fa237 // indirect
+	github.com/ribice/glice v0.0.0-20190726034412-e55bb973f127 // indirect
 	golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c
 	golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5 // indirect
 	golang.org/x/sys v0.0.0-20201207223542-d4d67f95c62d // indirect
diff --git a/go.sum b/go.sum
index c423bb0..cea5ef1 100644
--- a/go.sum
+++ b/go.sum
@@ -1,9 +1,109 @@
+cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/DataDog/zstd v1.4.4 h1:+IawcoXhCBylN7ccwdwf8LOH2jKq7NavGpEPanrlTzE=
 github.com/DataDog/zstd v1.4.4/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/DataDog/zstd v1.4.5 h1:EndNeuB0l9syBZhut0wns3gV1hL8zX8LIu6ZiVHWLIQ=
 github.com/DataDog/zstd v1.4.5/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
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+golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190219172222-a4c6cb3142f2/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190701094942-4def268fd1a4/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20191117063200-497ca9f6d64f/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876 h1:sKJQZMuxjOAR/Uo2LBfU90onWEf1dF4C+0hPJCc9Mpc=
 golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de h1:ikNHVSjEfnvz6sxdSPCaPt572qowuyMDMJLLm3Db3ig=
@@ -17,13 +117,26 @@ golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPI
 golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5 h1:2M3HP5CCK1Si9FQhwnzYhXdG6DXeebvUHFpre8QvbyI=
 golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
+golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20190724013045-ca1201d0de80/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914 h1:MlY3mEfbnWGmUi4rtHOtNnnnN4UJRGSyLPx+DXA5Sq4=
+golang.org/x/net v0.0.0-20191119073136-fc4aabc6c914/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/oauth2 v0.0.0-20190402181905-9f3314589c9a h1:tImsplftrFpALCYumobsd0K86vlAs/eXGFms2txfJfA=
+golang.org/x/oauth2 v0.0.0-20190402181905-9f3314589c9a/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
+golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20181205085412-a5c9d58dba9a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
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 golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191119060738-e882bf8e40c2/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200812155832-6a926be9bd1d h1:QQrM/CCYEzTs91GZylDCQjGHudbPTxF/1fvXdVh5lMo=
 golang.org/x/sys v0.0.0-20200812155832-6a926be9bd1d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -34,6 +147,23 @@ golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXR
 golang.org/x/term v0.0.0-20201207232118-ee85cb95a76b h1:a0ErnNnPKmhDyIXQvdZr+Lq8dc8xpMeqkF8y5PgQU4Q=
 golang.org/x/term v0.0.0-20201207232118-ee85cb95a76b/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190729092621-ff9f1409240a/go.mod h1:jcCCGcm9btYwXyDqrUWc6MKQKKGJCWEQ3AfLSRIbEuI=
+golang.org/x/tools v0.0.0-20191118222007-07fc4c7f2b98/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7 h1:EBZoQjiKKPaLbPrbpssUfuHtwM6KV/vb4U85g/cigFY=
 golang.org/x/tools v0.0.0-20200130002326-2f3ba24bd6e7/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/appengine v1.4.0 h1:/wp5JvzpHIxhs/dumFmF7BXTf3Z+dd4uXta4kVyO508=
+google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/src-d/go-billy.v4 v4.3.2 h1:0SQA1pRztfTFx2miS8sA97XvooFeNOmvUenF4o0EcVg=
+gopkg.in/src-d/go-billy.v4 v4.3.2/go.mod h1:nDjArDMp+XMs1aFAESLRjfGSgfvoYN0hDfzEk0GjC98=
+gopkg.in/src-d/go-git-fixtures.v3 v3.5.0/go.mod h1:dLBcvytrw/TYZsNTWCnkNF2DSIlzWYqTe3rJR56Ac7g=
+gopkg.in/src-d/go-git.v4 v4.13.1 h1:SRtFyV8Kxc0UP7aCHcijOMQGPxHSmMOPrzulQWolkYE=
+gopkg.in/src-d/go-git.v4 v4.13.1/go.mod h1:nx5NYcxdKxq5fpltdHnPa2Exj4Sx0EclMWZQbYDu2z8=
+gopkg.in/warnings.v0 v0.1.2 h1:wFXVbFY8DY5/xOe1ECiWdKCzZlxgshcYVNkBHstARME=
+gopkg.in/warnings.v0 v0.1.2/go.mod h1:jksf8JmL6Qr/oQM2OXTHunEvvTAsrWBLb6OOjuVWRNI=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/internal/clients/handlers/withcancel.go b/internal/clients/handlers/withcancel.go
deleted file mode 100644
index 7c9cf4e..0000000
--- a/internal/clients/handlers/withcancel.go
+++ /dev/null
@@ -1,24 +0,0 @@
-package handlers
-
-import "context"
-
-type withCancel struct {
-	ctx  context.Context
-	done chan struct{}
-}
-
-// WithCancel sets and returns the context used.
-func (w *withCancel) WithCancel(ctx context.Context) (context.Context, context.CancelFunc) {
-	cancelCtx, cancel := context.WithCancel(ctx)
-	w.ctx = cancelCtx
-
-	return cancelCtx, cancel
-}
-
-func (w *withCancel) Done() <-chan struct{} {
-	return w.done
-}
-
-func (w *withCancel) shutdown() {
-	close(w.done)
-}
diff --git a/internal/io/fs/permissions/permission.go b/internal/io/fs/permissions/permission.go
index 0ed4f17..cc5dd9b 100644
--- a/internal/io/fs/permissions/permission.go
+++ b/internal/io/fs/permissions/permission.go
@@ -1,4 +1,4 @@
-// +build !linux
+// +build !linuxacl
 
 package permissions
 
diff --git a/internal/io/fs/permissions/permission_linux.c b/internal/io/fs/permissions/permission_linuxacl.c
index cd10525..86b1185 100644
--- a/internal/io/fs/permissions/permission_linux.c
+++ b/internal/io/fs/permissions/permission_linuxacl.c
@@ -1,4 +1,6 @@
-#include "permission_linux.h"
+// +build linuxacl
+
+#include "permission_linuxacl.h"
 
 #ifdef DEBUG
 void debug_print_checker(struct permission_checker *pc) {
diff --git a/internal/io/fs/permissions/permission_linux.go b/internal/io/fs/permissions/permission_linuxacl.go
index bbc039b..7d2d7ca 100644
--- a/internal/io/fs/permissions/permission_linux.go
+++ b/internal/io/fs/permissions/permission_linuxacl.go
@@ -1,7 +1,9 @@
+// +build linuxacl
+
 package permissions
 
 /*
-#include "permission_linux.h"
+#include "permission_linuxacl.h"
 #cgo LDFLAGS: -L. -lacl
 */
 import "C"
diff --git a/internal/io/fs/permissions/permission_linux.h b/internal/io/fs/permissions/permission_linuxacl.h
index a2c266e..52dadcf 100644
--- a/internal/io/fs/permissions/permission_linux.h
+++ b/internal/io/fs/permissions/permission_linuxacl.h
@@ -1,3 +1,5 @@
+// +build linuxacl
+
 #ifndef PERMISSION_LINUX_H
 #define PERMISSION_LINUX_H
 
diff --git a/internal/io/fs/permissions/permission_test.go b/internal/io/fs/permissions/permission_test.go
index d415ac2..c0ef038 100644
--- a/internal/io/fs/permissions/permission_test.go
+++ b/internal/io/fs/permissions/permission_test.go
@@ -1,4 +1,4 @@
-// +build linux
+// +build linuxacl
 
 package permissions
 
diff --git a/internal/server/background/background.go b/internal/server/background/background.go
deleted file mode 100644
index 3907448..0000000
--- a/internal/server/background/background.go
+++ /dev/null
@@ -1,126 +0,0 @@
-package background
-
-import (
-	"context"
-	"errors"
-	"fmt"
-	"strings"
-	"sync"
-
-	"github.com/mimecast/dtail/internal/io/logger"
-)
-
-type job struct {
-	cancel context.CancelFunc
-	wg     *sync.WaitGroup
-}
-
-// Background specifies a job or command run in background on server side.
-// This does not require an active DTail client SSH connection/session.
-type Background struct {
-	mutex *sync.Mutex
-	jobs  map[string]job
-}
-
-// New returns a new background manager.
-func New() Background {
-	return Background{
-		jobs:  make(map[string]job),
-		mutex: &sync.Mutex{},
-	}
-}
-
-// Add a background job.
-func (b Background) Add(userName, jobName string, cancel context.CancelFunc, wg *sync.WaitGroup) error {
-	key := b.key(userName, jobName)
-	logger.Debug("background", "Add", key)
-
-	b.mutex.Lock()
-	defer b.mutex.Unlock()
-
-	if _, ok := b.jobs[key]; ok {
-		return errors.New("job already exists")
-	}
-
-	b.jobs[key] = job{cancel, wg}
-
-	// Clean up background job database.
-	go func() {
-		wg.Wait()
-		b.cancel(key)
-	}()
-
-	return nil
-}
-
-// Cancel a background job.
-func (b Background) Cancel(userName, jobName string) error {
-	key := b.key(userName, jobName)
-	logger.Debug("background", "Cancel", key)
-
-	return b.cancel(key)
-}
-
-func (b Background) cancel(key string) error {
-	job, ok := b.get(key)
-	logger.Debug("background", "cancel", key, job, ok)
-
-	if !ok {
-		return errors.New("no job to cancel")
-	}
-
-	logger.Debug("background", "cancel", "run job.cancel()")
-	job.cancel()
-	logger.Debug("background", "cancel", "run job.wg.Wait()")
-	job.wg.Wait()
-	logger.Debug("background", "cancel", "run b.delete(key)")
-	b.delete(key)
-
-	return nil
-}
-
-// ListJobsC returns a channel listing all jobs of the given user.
-func (b Background) ListJobsC(userName string) <-chan string {
-	logger.Debug("background", "ListJobC", userName)
-
-	ch := make(chan string)
-
-	go func() {
-		defer close(ch)
-
-		b.mutex.Lock()
-		defer b.mutex.Unlock()
-
-		for k := range b.jobs {
-			logger.Debug("ListJobsC", k, userName)
-			if strings.HasPrefix(k, fmt.Sprintf("%s.", userName)) {
-				ch <- k
-			}
-		}
-	}()
-
-	return ch
-}
-
-func (b Background) get(key string) (job, bool) {
-	logger.Debug("background", "get", key)
-
-	b.mutex.Lock()
-	defer b.mutex.Unlock()
-
-	job, ok := b.jobs[key]
-	return job, ok
-}
-
-func (b Background) delete(key string) {
-	logger.Debug("background", "delete", key)
-
-	b.mutex.Lock()
-	defer b.mutex.Unlock()
-
-	delete(b.jobs, key)
-}
-
-func (Background) key(userName, jobName string) string {
-	return fmt.Sprintf("%s.%s", userName, jobName)
-}