# Logging

If an error occurs in any of the processes it will be written to the respective log file such as `/var/log/overleaf/web.log`.

Toolkit users can have a look at the logs inside the container using the `bin/logs` script:

```bash
# You can use the following command to view the web service logs
bin/logs web

# You can use --help for help
bin/logs --help

# You can also look at the logs for multiple services at once:
bin/logs filestore docstore web clsi

# You can follow the log output using the -f flag
bin/logs -f filestore docstore web clsi

# You can use the -n {number} flag to limit the number of lines to print (default 50)
bin/logs -n 50 web

# You can use the -n all flag to show all log lines
bin/logs -n all web

# You can use > to redirect the output to a file
bin/logs -n all web > web.log
```

You can use the `bin/logs` script to view logs for the following services: `clsi`, `contacts`, `docstore`, `document-updater`, `filestore`, `git-bridge`, `mongo`, `notifications`, `real-time`, `redis`, `spelling`, `tags`, `track-changes`, `web`, `web-api`, `history-v1`, `project-history`.

## Copying logs

You can copy log files from the main `sharelatex` container to local computer using the following command:

```bash
docker cp sharelatex:/var/log/overleaf/{service-name}.log {service-name}.log
```

## Persisting logs

Docker containers are ephemeral which means that any files/directories created within the container during runtime will be discarded if the container is ever recreated (for example, when running the `bin/up` command). This **includes** log files. 

If you'd like to retain access to important log files between container recreation, you can set the environment variable `OVERLEAF_LOG_PATH` in the `config/overleaf.rc` file with the Toolkit. This variable should be set to the directory on the host that will be mounted to the log directory inside the `sharelatex` container. Once you've made this configuration change and run the `bin/up -d` command, log files will be persisted and you'll be able to access the logs directly from the Docker host.

{% hint style="danger" %}
You'll need to set the owner of the logs directory used in the bind-mount to the `www-data` user (uid=33) with the permissions `drwxr-xr-x` (755). 

As an example, you can can set the owner using `chown 33:33 data/overleaf/logs` and the permissions using `chmod 755 data/overleaf/logs`.
{% endhint %}


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