These kind of diagram are particularly helpful to developers and devops teams to share their Git branching strategies. For example, it makes it easier to visualize how git flow works.
Mermaid syntax for Gitgraph is very straight-forward and simple. It follows a declarative-approach, where each commit is drawn on the timeline in the diagram, in order of its occurrences/presence in code. Basically, it follows the insertion order for each command.
First thing you do is to declare your diagram type using the **gitgraph** keyword. This `gitgraph` keyword, tells Mermaid that you wish to draw a gitgraph, and parse the diagram code accordingly.
Each gitgraph, is initialized with ***main*** branch. So unless you create a different branch, by-default the commits will go to the main branch. This is driven with how git works, where in the begging you always start with the main branch (formerly called as ***master*** branch). And by-default, `main` branch is set as your ***current branch***.
You make use of ***commit*** keyword to register a commit on the current branch. Let see how this works:
A simple gitgraph showing three commits on the default (***main***) branch:
```mermaid-example
gitGraph
commit
commit
commit
```
If you look closely at the previous example, you can see the default branch `main` along with three commits. Also, notice, the by-default each commit has been given a unique & random Id. What if you would want to give your own custom ID to a commit? Yes, it is possible to do that with Mermaid.
### Adding custom commit id
For a given commit you may specify a custom id at the time of declaring it using the `id` attribute, followed by `:` and your custom value within `""` quote. For example: `commit id: "your_custom_id"`
Let us see how this works with the help of the following diagram:
```mermaid-example
gitGraph
commit id: "Alpha"
commit id: "Beta"
commit id: "Gamma"
```
In this example, we have given our custom id's to the commits.
### Modifying commit type
In Mermaid, a commit can be of three type, which render a bit different in the diagram. These types are:
-`NORMAL` : Default commit type. Represented by a solid circle in the diagram
-`REVERSE` : To emphasize a commit as a reverse commit. Represented by a crossed solid circle in the diagram.
-`HIGHLIGHT` : To highlight a particular commit in the diagram. Represented by a filled rectangle in the diagram.
For a given commit you may specify its type at the time of declaring it using the `type` attribute, followed by `:` and the required type option discussed above. For example: `commit type: HIGHLIGHT`
NOTE: If no commit type is specified, `NORMAL` is picked as default.
Let us see how these different commit type look with the help of the following diagram:
In this example, we have specified different types to each commit. Also, see how we have clubbed both `id` and `type` together at the time of declaring our commits.
### Adding Tags
For a given commit you may decorate it as a **tag**, similar to the concept of tags or release version in git world.
You can attach a custom tag at the time of declaring a commit using the `tag` attribute, followed by `:` and your custom value within `""` quote. For example: `commit tag: "your_custom_tag"`
Let us see how this works with the help of the following diagram:
In this example, we have given custom tags to the commits. Also, see how we have combined all these attributes in a single commit declaration. You can mix-match these attributes as you like.
In Mermaid, in-order to create a new branch, you make use of the `branch` keyword. You also need to provide a name of the new branch. The name has to be unique and cannot be that of an existing branch. Usage example: `branch develop`
When Mermaid, reads the `branch` keyword, it creates a new branch and sets it as the current branch. Equivalent to you creating a new branch and checking it out in Git world.
Let see this in an example:
```mermaid-example
gitGraph
commit
commit
branch develop
commit
commit
commit
```
In this example, see how we started with default `main` branch, and pushed to commits on that.
Then we created the `develop` branch, and all commits afterwards are put on the `develop` branch as it became the current branch.
### Checking out an existing branch
In Mermaid, in-order to switch to an existing branch, you make use of the `checkout` keyword. You also need to provide a name of an existing branch. If no branch is found with the given name, it will result in console error. Usage example: `checkout develop`
When Mermaid, reads the `checkout` keyword, it finds the given branch and sets it as the current branch. Equivalent to checking out a branch in Git world.
Let see modify our previous example:
```mermaid-example
gitGraph
commit
commit
branch develop
commit
commit
commit
checkout main
commit
commit
```
In this example, see how we started with default `main` branch, and pushed to commits on that.
Then we created the `develop` branch, and all three commits afterwards are put on the `develop` branch as it became the current branch.
After this we made use of the `checkout` keyword to set the current branch as `main`, and all commit that follow are registered against the current branch, i.e. `main`.
### Merging two branches
In Mermaid, in-order to merge or join to an existing branch, you make use of the `merge` keyword. You also need to provide a name of an existing branch to merge from. If no branch is found with the given name, it will result in console error. Also, if you can only merge two separate branches, and cannot merge a branch with itself. In such case an error is throw.
Usage example: `merge develop`
When Mermaid, reads the `merge` keyword, it finds the given branch and its head commit (the last commit on that branch), and joins it with the head commit on the **current branch**. Each merge result in a ***merge commit***, represented in the diagram with **filled double circle**.
Let see modify our previous example to merge our two branches:
```mermaid-example
gitGraph
commit
commit
branch develop
commit
commit
commit
checkout main
commit
commit
merge develop
commit
commit
```
In this example, see how we started with default `main` branch, and pushed to commits on that.
Then we created the `develop` branch, and all three commits afterwards are put on the `develop` branch as it became the current branch.
After this we made use of the `checkout` keyword to set the current branch as `main`, and all commit that follow are registered against the current branch, i.e. `main`.
After this we merge the `develop` branch onto the current branch `main`, resulting in a merge commit.
Since the current branch at this point is still `main`, the last two commits are registered against that.
In Mermaid, you have the option to configure the gitgraph diagram. You can configure the following options:
-`showBranches` : Boolean, default is `true`. If set to `false`, the branches are not shown in the diagram.
-`showCommitLabel` : Boolean, default is `true`. If set to `false`, the commit labels are not shown in the diagram.
-`mainBranchName` : String, default is `main`. The name of the default/root branch.
Let's look at them one by one.
## Hiding Branch names and lines
Sometimes you may want to hide the branch names and lines from the diagram. You can do this by using the `showBranches` keyword. Bye default its value is `true`. You can set it to false using directives
Sometimes you may want to hide the commit labels from the diagram. You can do this by using the `showCommitLabel` keyword. By default its value is `true`. You can set it to `false` using directives.
Sometimes you may want to customize the name of the main/default branch. You can do this by using the `mainBranchName` keyword. By default its value is `main`. You can set it to any string using directives.
Mermaid supports a bunch of pre-defined themes which you can use to find the right one for you. PS: you can actually override an existing theme's variable to get your own custom theme going. Learn more about theming your diagram [here](./theming.md).
Mermaid allows you to customize your diagram using theme variables which govern the look and feel of various elements of the diagram.
For understanding let us take a sample diagram with theme `default`, the default values of the theme variables is picked automatically from the theme. Later on we will see how to override the default values of the theme variables.
See how the default theme is used to set the colors for the branches:
You can customize the branch colors using the `git0` to `git7` theme variables. Mermaid allows you to set the colors for up-to 8 branches, where `git0` variable will drive the value of the first branch, `git1` will drive the value of the second branch and so on.
NOTE: Default values for these theme variables are picked from the selected theme. If you want to override the default values, you can use the `initialize` call to add your custom theme variable values.
Example:
Now let's override the default values for the `git0` to `git3` variables:
See how the branch colors are changed to the values specified in the theme variables.
### Customizing branch label colors
You can customize the branch label colors using the `gitBranchLabel0` to `gitBranchLabel7` theme variables. Mermaid allows you to set the colors for up-to 8 branches, where `gitBranchLabel0` variable will drive the value of the first branch label, `gitBranchLabel1` will drive the value of the second branch label and so on.
Lets see how the default theme is used to set the colors for the branch labels:
Now let's override the default values for the `gitBranchLabel0` to `gitBranchLabel2` variables:
See how the branch label colors are changed to the values specified in the theme variables.
### Customizing Commit colors
You can customize commit using the `commitLabelColor` and `commitLabelBackground` theme variables for changes in the commit label color and background color respectively.
Example:
Now let's override the default values for the `commitLabelColor` to `commitLabelBackground` variables:
See how the commit label color and background color are changed to the values specified in the theme variables.
### Customizing Tag colors
You can customize tag using the `tagLabelColor`,`tagLabelBackground` and `tagLabelBorder` theme variables for changes in the tag label color,tag label background color and tag label border respectively.
Example:
Now let's override the default values for the `tagLabelColor`, `tagLabelBackground` and to `tagLabelBorder` variables:
See how the tag colors are changed to the values specified in the theme variables.
### Customizing Highlight commit colors
You can customize the highlight commit colors in relation to the branch it is on using the `gitInv0` to `gitInv7` theme variables. Mermaid allows you to set the colors for up-to 8 branches specific highlight commit, where `gitInv0` variable will drive the value of the first branch's highlight commits, `gitInv1` will drive the value of the second branch's highlight commit label and so on.
Example:
Now let's override the default values for the `git0` to `git3` variables:
