github.com/aclaygray/packer@v1.3.2/website/source/docs/provisioners/shell.html.md (about) 1 --- 2 description: | 3 The shell Packer provisioner provisions machines built by Packer using shell 4 scripts. Shell provisioning is the easiest way to get software installed and 5 configured on a machine. 6 layout: docs 7 page_title: 'Shell - Provisioners' 8 sidebar_current: 'docs-provisioners-shell-remote' 9 --- 10 11 # Shell Provisioner 12 13 Type: `shell` 14 15 The shell Packer provisioner provisions machines built by Packer using shell 16 scripts. Shell provisioning is the easiest way to get software installed and 17 configured on a machine. 18 19 -> **Building Windows images?** You probably want to use the 20 [PowerShell](/docs/provisioners/powershell.html) or [Windows 21 Shell](/docs/provisioners/windows-shell.html) provisioners. 22 23 ## Basic Example 24 25 The example below is fully functional. 26 27 ``` json 28 { 29 "type": "shell", 30 "inline": ["echo foo"] 31 } 32 ``` 33 34 ## Configuration Reference 35 36 The reference of available configuration options is listed below. The only 37 required element is either "inline" or "script". Every other option is optional. 38 39 Exactly *one* of the following is required: 40 41 - `inline` (array of strings) - This is an array of commands to execute. The 42 commands are concatenated by newlines and turned into a single file, so they 43 are all executed within the same context. This allows you to change 44 directories in one command and use something in the directory in the next 45 and so on. Inline scripts are the easiest way to pull off simple tasks 46 within the machine. 47 48 - `script` (string) - The path to a script to upload and execute in 49 the machine. This path can be absolute or relative. If it is relative, it is 50 relative to the working directory when Packer is executed. 51 52 - `scripts` (array of strings) - An array of scripts to execute. The scripts 53 will be uploaded and executed in the order specified. Each script is 54 executed in isolation, so state such as variables from one script won't 55 carry on to the next. 56 57 Optional parameters: 58 59 - `binary` (boolean) - If true, specifies that the script(s) are binary files, 60 and Packer should therefore not convert Windows line endings to Unix line 61 endings (if there are any). By default this is false. 62 63 - `environment_vars` (array of strings) - An array of key/value pairs to 64 inject prior to the execute\_command. The format should be `key=value`. 65 Packer injects some environmental variables by default into the environment, 66 as well, which are covered in the section below. 67 68 - `use_env_var_file` (boolean) - If true, Packer will write your environment 69 variables to a tempfile and source them from that file, rather than 70 declaring them inline in our execute_command. The default `execute_command` 71 will be `chmod +x {{.Path}}; . {{.EnvVarFile}} && {{.Path}}`. This option is 72 unnecessary for most cases, but if you have extra quoting in your custom 73 `execute_command`, then this may be unnecessary for proper script execution. 74 Default: false. 75 76 - `execute_command` (string) - The command to use to execute the script. By 77 default this is `chmod +x {{ .Path }}; {{ .Vars }} {{ .Path }}`, unless the 78 user has set `"use_env_var_file": true` -- in that case, the default 79 `execute_command` is `chmod +x {{.Path}}; . {{.EnvVarFile}} && {{.Path}}`. 80 The value of this is treated as a 81 [configuration template](/docs/templates/engine.html). There are three 82 available variables: 83 * `Path` is the path to the script to run 84 * `Vars` is the list of `environment_vars`, if configured. 85 * `EnvVarFile` is the path to the file containing env vars, if 86 `use_env_var_file` is true. 87 - `expect_disconnect` (boolean) - Defaults to `false`. Whether to error if the 88 server disconnects us. A disconnect might happen if you restart the ssh 89 server or reboot the host. 90 91 - `inline_shebang` (string) - The 92 [shebang](https://en.wikipedia.org/wiki/Shebang_%28Unix%29) value to use when 93 running commands specified by `inline`. By default, this is `/bin/sh -e`. If 94 you're not using `inline`, then this configuration has no effect. 95 **Important:** If you customize this, be sure to include something like the 96 `-e` flag, otherwise individual steps failing won't fail the provisioner. 97 98 - `remote_folder` (string) - The folder where the uploaded script will reside on 99 the machine. This defaults to '/tmp'. 100 101 - `remote_file` (string) - The filename the uploaded script will have on the machine. 102 This defaults to 'script\_nnn.sh'. 103 104 - `remote_path` (string) - The full path to the uploaded script will have on the 105 machine. By default this is remote\_folder/remote\_file, if set this option will 106 override both remote\_folder and remote\_file. 107 108 - `skip_clean` (boolean) - If true, specifies that the helper scripts 109 uploaded to the system will not be removed by Packer. This defaults to 110 false (clean scripts from the system). 111 112 - `start_retry_timeout` (string) - The amount of time to attempt to *start* 113 the remote process. By default this is `5m` or 5 minutes. This setting 114 exists in order to deal with times when SSH may restart, such as a 115 system reboot. Set this to a higher value if reboots take a longer amount 116 of time. 117 118 ## Execute Command Example 119 120 To many new users, the `execute_command` is puzzling. However, it provides an 121 important function: customization of how the command is executed. The most 122 common use case for this is dealing with **sudo password prompts**. You may also 123 need to customize this if you use a non-POSIX shell, such as `tcsh` on FreeBSD. 124 125 ### Sudo Example 126 127 Some operating systems default to a non-root user. For example if you login as 128 `ubuntu` and can sudo using the password `packer`, then you'll want to change 129 `execute_command` to be: 130 131 ``` text 132 "echo 'packer' | sudo -S sh -c '{{ .Vars }} {{ .Path }}'" 133 ``` 134 135 The `-S` flag tells `sudo` to read the password from stdin, which in this case 136 is being piped in with the value of `packer`. 137 138 The above example won't work if your environment vars contain spaces or single quotes; in these cases try removing the single quotes: 139 140 ``` text 141 "echo 'packer' | sudo -S env {{ .Vars }} {{ .Path }}" 142 ``` 143 144 By setting the `execute_command` to this, your script(s) can run with root 145 privileges without worrying about password prompts. 146 147 ### FreeBSD Example 148 149 FreeBSD's default shell is `tcsh`, which deviates from POSIX semantics. In order 150 for packer to pass environment variables you will need to change the 151 `execute_command` to: 152 153 ``` text 154 chmod +x {{ .Path }}; env {{ .Vars }} {{ .Path }} 155 ``` 156 157 Note the addition of `env` before `{{ .Vars }}`. 158 159 ## Default Environmental Variables 160 161 In addition to being able to specify custom environmental variables using the 162 `environment_vars` configuration, the provisioner automatically defines certain 163 commonly useful environmental variables: 164 165 - `PACKER_BUILD_NAME` is set to the 166 [name of the build](/docs/templates/builders.html#named-builds) that Packer is running. 167 This is most useful when Packer is making multiple builds and you want to 168 distinguish them slightly from a common provisioning script. 169 170 - `PACKER_BUILDER_TYPE` is the type of the builder that was used to create the 171 machine that the script is running on. This is useful if you want to run 172 only certain parts of the script on systems built with certain builders. 173 174 - `PACKER_HTTP_ADDR` If using a builder that provides an http server for file 175 transfer (such as hyperv, parallels, qemu, virtualbox, and vmware), this 176 will be set to the address. You can use this address in your provisioner to 177 download large files over http. This may be useful if you're experiencing 178 slower speeds using the default file provisioner. A file provisioner using 179 the `winrm` communicator may experience these types of difficulties. 180 181 ## Handling Reboots 182 183 Provisioning sometimes involves restarts, usually when updating the operating 184 system. Packer is able to tolerate restarts via the shell provisioner. 185 186 Packer handles this by retrying to start scripts for a period of time before 187 failing. This allows time for the machine to start up and be ready to run 188 scripts. The amount of time the provisioner will wait is configured using 189 `start_retry_timeout`, which defaults to a few minutes. 190 191 Sometimes, when executing a command like `reboot`, the shell script will return 192 and Packer will start executing the next one before SSH actually quits and the 193 machine restarts. For this, put use "pause\_before" to make Packer wait before executing the next script: 194 195 ``` json 196 { 197 "type": "shell", 198 "script": "script.sh", 199 "pause_before": "10s" 200 } 201 ``` 202 203 Some OS configurations don't properly kill all network connections on reboot, 204 causing the provisioner to hang despite a reboot occurring. In this case, make 205 sure you shut down the network interfaces on reboot or in your shell script. For 206 example, on Gentoo: 207 208 ``` text 209 /etc/init.d/net.eth0 stop 210 ``` 211 212 ## SSH Agent Forwarding 213 214 Some provisioning requires connecting to remote SSH servers from within the 215 packer instance. The below example is for pulling code from a private git 216 repository utilizing openssh on the client. Make sure you are running 217 `ssh-agent` and add your git repo ssh keys into it using `ssh-add /path/to/key`. 218 When the packer instance needs access to the ssh keys the agent will forward the 219 request back to your `ssh-agent`. 220 221 Note: when provisioning via git you should add the git server keys into the 222 `~/.ssh/known_hosts` file otherwise the git command could hang awaiting input. 223 This can be done by copying the file in via the [file 224 provisioner](/docs/provisioners/file.html) (more secure) or using `ssh-keyscan` 225 to populate the file (less secure). An example of the latter accessing github 226 would be: 227 228 ``` json 229 { 230 "type": "shell", 231 "inline": [ 232 "sudo apt-get install -y git", 233 "ssh-keyscan github.com >> ~/.ssh/known_hosts", 234 "git clone git@github.com:exampleorg/myprivaterepo.git" 235 ] 236 } 237 ``` 238 239 ## Troubleshooting 240 241 *My shell script doesn't work correctly on Ubuntu* 242 243 - On Ubuntu, the `/bin/sh` shell is 244 [dash](https://en.wikipedia.org/wiki/Debian_Almquist_shell). If your script 245 has [bash](https://en.wikipedia.org/wiki/Bash_(Unix_shell))-specific 246 commands in it, then put `#!/bin/bash -e` at the top of your script. 247 Differences between dash and bash can be found on the 248 [DashAsBinSh](https://wiki.ubuntu.com/DashAsBinSh) Ubuntu wiki page. 249 250 *My shell works when I login but fails with the shell provisioner* 251 252 - See the above tip. More than likely, your login shell is using `/bin/bash` 253 while the provisioner is using `/bin/sh`. 254 255 *My installs hang when using `apt-get` or `yum`* 256 257 - Make sure you add a `-y` to the command to prevent it from requiring user 258 input before proceeding. 259 260 *How do I tell what my shell script is doing?* 261 262 - Adding a `-x` flag to the shebang at the top of the script (`#!/bin/sh -x`) 263 will echo the script statements as it is executing. 264 265 *My builds don't always work the same* 266 267 - Some distributions start the SSH daemon before other core services which can 268 create race conditions. Your first provisioner can tell the machine to wait 269 until it completely boots. 270 271 ```json 272 { 273 "type": "shell", 274 "inline": [ "sleep 10" ] 275 } 276 ``` 277 278 ## Quoting Environment Variables 279 280 Packer manages quoting for you, so you should't have to worry about it. 281 Below is an example of packer template inputs and what you should expect to get 282 out: 283 284 ```json 285 "provisioners": [ 286 { 287 "type": "shell", 288 "environment_vars": ["FOO=foo", 289 "BAR=bar's", 290 "BAZ=baz=baz", 291 "QUX==qux", 292 "FOOBAR=foo bar", 293 "FOOBARBAZ='foo bar baz'", 294 "QUX2=\"qux\""], 295 "inline": ["echo \"FOO is $FOO\"", 296 "echo \"BAR is $BAR\"", 297 "echo \"BAZ is $BAZ\"", 298 "echo \"QUX is $QUX\"", 299 "echo \"FOOBAR is $FOOBAR\"", 300 "echo \"FOOBARBAZ is $FOOBARBAZ\"", 301 "echo \"QUX2 is $QUX2\""] 302 } 303 ``` 304 305 Output: 306 307 ``` 308 docker: FOO is foo 309 docker: BAR is bar's 310 docker: BAZ is baz=baz 311 docker: QUX is =qux 312 docker: FOOBAR is foo bar 313 docker: FOOBARBAZ is 'foo bar baz' 314 docker: QUX2 is "qux" 315 ```