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+# Hooks
+You can define arbitrary number of hooks that subscribe different events. The hook system is modular and different kind of hook types can be enabled.
+
+## Configuration
+Following configuration keys need to be defined for all hooks:
+
+  * `events`: which events to subscribe. Needs to be an array. See below for the list of available events.
+  * `type`: what hook class to use. See below for the list of available hook types.
+
+### Events
+  * `node_success`: triggered when configuration is succesfully pulled from a node and right before storing the configuration.
+  * `node_fail`: triggered after `retries` amount of failed node pulls.
+  * `post_store`: triggered after node configuration is stored (this is executed only when the configuration has changed).
+  * `nodes_done`: triggered after finished fetching all nodes.
+
+## Hook type: exec
+The `exec` hook type allows users to run an arbitrary shell command or a binary when triggered.
+
+The command is executed on a separate child process either in synchronous or asynchronous fashion. Non-zero exit values cause errors to be logged. STDOUT and STDERR are currently not collected.
+
+Command is executed with the following environment:
+```
+OX_EVENT
+OX_NODE_NAME
+OX_NODE_IP
+OX_NODE_FROM
+OX_NODE_MSG
+OX_NODE_GROUP
+OX_JOB_STATUS
+OX_JOB_TIME
+OX_REPO_COMMITREF
+OX_REPO_NAME
+```
+
+Exec hook recognizes following configuration keys:
+
+  * `timeout`: hard timeout for the command execution. SIGTERM will be sent to the child process after the timeout has elapsed. Default: 60
+  * `async`: influences whether main thread will wait for the command execution. Set this true for long running commands so node pull is not blocked. Default: false
+  * `cmd`: command to run.
+
+
+## Hook configuration example
+```
+hooks:
+  name_for_example_hook1:
+    type: exec
+    events: [node_success]
+    cmd: 'echo "Node success $OX_NODE_NAME" >> /tmp/ox_node_success.log'
+  name_for_example_hook2:
+    type: exec
+    events: [post_store, node_fail]
+    cmd: 'echo "Doing long running stuff for $OX_NODE_NAME" >> /tmp/ox_node_stuff.log; sleep 60'
+    async: true
+    timeout: 120
+```
+
+### githubrepo
+
+This hook configures the repository `remote` and _push_ the code when the specified event is triggerd. If the `username` and `password` are not provided, the `Rugged::Credentials::SshKeyFromAgent` will be used.
+
+`githubrepo` hook recognizes following configuration keys:
+
+  * `remote_repo`: the remote repository to be pushed to.
+  * `username`: username for repository auth.
+  * `password`: password for repository auth.
+  * `publickey`: publickey for repository auth.
+  * `privatekey`: privatekey for repository auth.
+
+When using groups repositories, each group must have its own `remote` in the `remote_repo` config.
+
+``` yaml
+hooks:
+  push_to_remote:
+    remote_repo:
+      routers: git@git.intranet:oxidized/routers.git
+      switches: git@git.intranet:oxidized/switches.git
+      firewalls: git@git.intranet:oxidized/firewalls.git
+```
+
+
+## Hook configuration example
+
+``` yaml
+hooks:
+  push_to_remote:
+    type: githubrepo
+    events: [post_store]
+    remote_repo: git@git.intranet:oxidized/test.git
+    username: user
+    password: pass
+```
+
+## Hook type: awssns
+
+The `awssns` hook publishes messages to AWS SNS topics. This allows you to notify other systems of device configuration changes, for example a config orchestration pipeline. Multiple services can subscribe to the same AWS topic.
+
+Fields sent in the message:
+
+  * `event`: Event type (e.g. `node_success`)
+  * `group`: Group name
+  * `model`: Model name (e.g. `eos`)
+  * `node`: Device hostname
+
+Configuration example:
+
+``` yaml
+hooks:
+  hook_script:
+    type: awssns
+    events: [node_fail,node_success,post_store]
+    region: us-east-1
+    topic_arn: arn:aws:sns:us-east-1:1234567:oxidized-test-backup_events
+```
+
+AWS SNS hook requires the following configuration keys:
+
+  * `region`: AWS Region name
+  * `topic_arn`: ASN Topic reference
+
+Your AWS credentials should be stored in `~/.aws/credentials`.
+
+## Hook type: slackdiff
+
+The `slackdiff` hook posts colorized config diffs to a [Slack](http://www.slack.com) channel of your choice. It only triggers for `post_store` events.
+
+You will need to manually install the `slack-api` gem on your system:
+
+```
+gem install slack-api
+```
+
+Configuration example:
+
+``` yaml
+hooks:
+  slack:
+    type: slackdiff
+    events: [post_store]
+    token: SLACK_BOT_TOKEN
+    channel: "#network-changes"
+```
+
+Note the channel name must be in quotes.