Re: Location limits on development, staging and production environments

[H <agents@meddatainc.com>]

On 01/29/2018 10:02 PM, Bryan Turner wrote:
> On Mon, Jan 29, 2018 at 11:08 AM, H <agents@meddatainc.com> wrote:
>> I am a newcomer to git looking to set up a web development environment where individual computers are used for development, the development.git, staging.git and production.git repositories are stored on an external server reachable by password-less ssh and the staging and production websites are on yet another server, also reachable by password-less ssh from the git-server (and the development machines).
>>
>> Locating the three git repositories on an external server works fine but I have not been able to have the staging and production deployment files on another server. I believe this is what is referred by GIT_WORK_TREE and based on what I found on the web I created a post-receive hook of staging.git with the two lines:
>>
>> #!/bin/sh
>> GIT_WORK_TREE=user@1.2.3.4:/var/www/html/dev.whatever git checkout -f master
>>
>> I believe this should deploy the files from the development work tree.
>>
>> The above, however, fails. Should it work? I am running git 1.7.1 on CentOS 6.
> No, I wouldn't expect that to work. GIT_WORK_TREE is not remote-aware
> in that way. It's expected to be a normal-ish filesystem path.
>
> Based on your description, and the hook you've written, it seems like
> your intention is for the source to automatically be fetched and
> checked out on the staging environment after each push. (This is
> dangerous, and likely _not_ what you actually want, but I'll get to
> that in a moment.)
>
> One option would be to setup something like NFS, so the git-server can
> mount the filesystems from the staging and production nodes.
>
> A different, likely better, option would be to have the post-receive
> script on the git-server use straight ssh to trigger a checkout script
> on the staging server, e.g.:
> #!/bin/sh
> ssh example@staging-server -C /opt/deploy-staging.sh
>
> Your deploy-staging script would then do something like:
> #!/bin/sh
> GIT_WORK_TREE=/var/www/html/dev.whatever git pull origin
>
> That said, though, having such a simple script is dangerous because
> Git is fully capable of having receiving multiple pushes concurrently,
> and they can all succeed as long as they're updating different
> branches. Since your script isn't considering what branches were
> changed by the push, it could end up triggering simultaneous git
> processes on the staging server all attempting to deploy concurrently.
>
> The stdin for the post-receive hook receives details about which refs
> were changed, and you'll likely want to update your script to parse
> stdin and only try to deploy staging if a specific, relevant branch
> (master in your example) has changed.
>
> Lastly, I'll note that using post-receive will make the pushing
> (remote) user wait while the staging server is deployed. If that
> process is likely to take very long, you might want to decouple the
> two somehow.
>
> Hope this helps!

I should perhaps also have mentioned that although I am the only developer, I may use different computers to develop on. IOW, there should not be any conflict due to code being pushed by multiple developers.

Let's see if I understand this correctly:

- Unless NFS is used, the git archive and the deployment of the website code in this case should reside on the same computer.

- The combination of the checkout script and the deploy-staging script should work provided not multiple updates to the same branch are pushed at the same time.

I will try this later today but any other hints or suggestions you may have would be greatly appreciated!