SSH Agent, SSH Keys/Identities, Composer, Repositories in composer.json on Windows 11

So my client shared a repository on a private GitLab platform with me. I have access to the platform and the repo and added SSH key to my account that I generated using PuTTY Gen. I then used TortoiseGit to clone it using my SSH key. It worked as expected and the repository was cloned into the WWW directory of my WAMP server. 

Then I used Git Bash to execute the following command to install composer packages

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1	composer install

It showed some errors like this extension is required, that extension is missing. To avoid these errors for now, I ran the following command

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1	composer install --ignore-platform-reqs

It executed and then at some point it started asking me for password. I noticed that its a different repository. I looked into the composer.json and found that it requires another repo. I asked client to grant me permission for the repo and he instantly gave that. I tried again and again, but composer install keep failing due to some password instead of asking for passphrase of my private key.

So to fix this, I first had to check if I can SSH to the GitLab platform. So I ran the following command

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1	ssh -i path/to/my/private/key -T git@gitlab.inchev.com

It asked for my passphrase and then it said welcome.

Now I had to add my SSH identity to Git Agent, so I ran

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1	ssh-add path/to/my/private/key

And this command gave me the following error

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1	Could not open a connection to your authentication agent.

After asking ChatGPT about this error, it said that my SSH agent is not running and I have to run this command first to run SSH agent

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1	eval $(ssh-agent)

As soon as I ran this it showed 

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1	Agent pid 1755

This mean that my SSH agent is now running. So I ran the previous command again which is

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1	ssh-add path/to/my/private/key

It then asked for the passphrase and then it confirmed that my identity was added. Then I ran the composer install command and it worked as expected

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1	composer install --ignore-platform-reqs

I learnt that,

1. there is something called SSH agent which I have to start. However I still don't know if I have to run this manually each time or not or what is the use of this thing
2. there can be a section called repositories in composer.json 
3. I can add my SSH key to SSH agent and it won't ask for passphrase again
4. I can use --ignore-platform-reqs when running composer install command to avoid platform requirements by composer

Forgot to mention, I also created SSH key using the Git Bash as it was saying the key that I generated using PuTTY Gen. Let see how I did that

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1	ssh-keygen -t ed25519 -C "your_email@example.com"

Here I placed my that email address that I used to login to my account on that given Git Platform

It asked for where to save the keys, I entered the following

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1	d:/my-keys/new-key

Then it asked for my passphrase, I entered that

Then the process completed