Gitgraph Diagrams

A Git Graph is a pictorial representation of git commits and git actions(commands) on various branches.

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 can render Git diagrams

In Mermaid, we support the basic git operations like:

• commit : Representing a new commit on the current branch.
• branch : To create & switch to a new branch, setting it as the current branch.
• checkout : To checking out an existing branch and setting it as the current branch.
• merge : To merge an existing branch onto the current branch.

With the help of these key git commands, you will be able to draw a gitgraph in Mermaid very easily and quickly. Entity names are often capitalized, although there is no accepted standard on this, and it is not required in Mermaid.

Syntax

Mermaid syntax for a 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 beginning 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:

If you look closely at the previous example, you can see the default branch main along with three commits. Also, notice that by default each commit has been given a unique & random ID. What if you wanted 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 a "" quote. For example: commit id: "your_custom_id"

Let us see how this works with the help of the following diagram:

In this example, we have given our custom IDs 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 included 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.

Create a new branch

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. A branch name that could be confused for a keyword must be quoted within "". Usage examples: branch develop, branch "cherry-pick"

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:

In this example, see how we started with default main branch, and pushed two 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 the Git world.

Let see modify our previous example:

In this example, see how we started with default main branch, and pushed two 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 the name of an existing branch to merge from. If no branch is found with the given name, it will result in console error. Also, 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 results in a merge commit, represented in the diagram with filled double circle.

Let us modify our previous example to merge our two branches:

In this example, see how we started with default main branch, and pushed two 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 commits 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.

You can also decorate your merge with similar attributes as you did for the commit using:

• id--> To override the default ID with custom ID
• tag--> To add a custom tag to your merge commit
• type--> To override the default shape of merge commit. Here you can use other commit type mentioned earlier.

And you can choose to use none, some or all of these attributes together. For example: merge develop id: "my_custom_id" tag: "my_custom_tag" type: REVERSE

Let us see how this works with the help of the following diagram:

Cherry Pick commit from another branch

Similar to how 'git' allows you to cherry-pick a commit from another branch onto the current branch, Mermaid also supports this functionality. You can also cherry-pick a commit from another branch using the cherry-pick keyword.

To use the cherry-pick keyword, you must specify the id using the id attribute, followed by : and your desired commit id within a "" quote. For example:

cherry-pick id: "your_custom_id"

Here, a new commit representing the cherry-pick is created on the current branch, and is visually highlighted in the diagram with a cherry and a tag depicting the commit id from which it is cherry-picked from.

A few important rules to note here are:

1. You need to provide the id for an existing commit to be cherry-picked. If given commit id does not exist it will result in an error. For this, make use of the commit id:$value format of declaring commits. See the examples from above.
2. The given commit must not exist on the current branch. The cherry-picked commit must always be a different branch than the current branch.
3. Current branch must have at least one commit, before you can cherry-pick, otherwise it will cause an error is throw.
4. When cherry-picking a merge commit, providing a parent commit ID is mandatory. If the parent attribute is omitted or an invalid parent commit ID is provided, an error will be thrown.
5. The specified parent commit must be an immediate parent of the merge commit being cherry-picked.

Let see an example:

Gitgraph specific configuration options

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.
• mainBranchOrder : Position of the main branch in the list of branches. default is 0, meaning, by default main branch is the first in the order.
• parallelCommits: Boolean, default is false. If set to true, commits x distance away from the parent are shown at the same level in the diagram.

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. By default its value is true. You can set it to false using directives.

Usage example:

Commit labels Layout: Rotated or Horizontal

Mermaid supports two types of commit labels layout. The default layout is rotated, which means the labels are placed below the commit circle, rotated at 45 degrees for better readability. This is particularly useful for commits with long labels.

The other option is horizontal, which means the labels are placed below the commit circle centred horizontally, and are not rotated. This is particularly useful for commits with short labels.

You can change the layout of the commit labels by using the rotateCommitLabel keyword in the directive. It defaults to true, which means the commit labels are rotated.

Usage example: Rotated commit labels

Usage example: Horizontal commit labels

Hiding commit labels

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.

Usage example:

Customizing main branch name

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.

Usage example:

Look at the imaginary railroad map created using Mermaid. Here, we have changed the default main branch name to MetroLine1.

Customizing branch ordering

In Mermaid, by default the branches are shown in the order of their definition or appearance in the diagram code.

Sometimes you may want to customize the order of the branches. You can do this by using the order keyword next the branch definition. You can set it to a positive number.

Mermaid follows the given precedence order of the order keyword.

• Main branch is always shown first as it has default order value of 0. (unless its order is modified and changed from 0 using the mainBranchOrder keyword in the config)
• Next, All branches without an order are shown in the order of their appearance in the diagram code.
• Next, All branches with an order are shown in the order of their order value.

To fully control the order of all the branches, you must define order for all the branches.

Usage example:

Look at the diagram, all the branches are following the order defined.

Usage example:

Look at the diagram, here, all the branches without a specified order are drawn in their order of definition. Then, test4 branch is drawn because the order of 1. Then, main branch is drawn because the order of 2. And, lastly test1is drawn because the order of 3.

NOTE: Because we have overridden the mainBranchOrder to 2, the main branch is not drawn in the beginning, instead follows the ordering.

Here, we have changed the default main branch name to MetroLine1.

Orientation (v10.3.0+)

Mermaid supports two graph orientations: Left-to-Right (default) and Top-to-Bottom.

You can set this with either LR: (for Left-to-Right) or TB: (for Top-to-Bottom) after gitGraph.

Left to Right (default, LR:)

In Mermaid, the default orientation is for commits to run from left to right and for branches to be stacked on top of one another.

However, you can set this explicitly with LR: after gitGraph.

Usage example:

Top to Bottom (TB:)

In TB (Top-to-Bottom) orientation, the commits run from top to bottom of the graph and branches are arranged side-by-side.

To orient the graph this way, you need to add TB: after gitGraph.

Usage example:

Parallel commits (v10.8.0+)

Commits in Mermaid display temporal information in gitgraph by default. For example if two commits are one commit away from its parent, the commit that was made earlier is rendered closer to its parent. You can turn this off by enabling the parallelCommits flag.

Temporal Commits (default, parallelCommits: false)

Parallel commits (parallelCommits: true)

Themes

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.

The following are the different pre-defined theme options:

• base
• forest
• dark
• default
• neutral

NOTE: To change theme you can either use the initialize call or directives. Learn more about directives Let's put them to use, and see how our sample diagram looks in different themes:

Base Theme

Forest Theme

Default Theme

Dark Theme

Neutral Theme

Customize using Theme Variables

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:

IMPORTANT:

Mermaid supports the theme variables to override the default values for up to 8 branches, i.e., you can set the color/styling of up to 8 branches using theme variables. After this threshold of 8 branches, the theme variables are reused in the cyclic manner, i.e. the 9th branch will use the color/styling of the 1st branch, or the branch at index position '8' will use the color/styling of the branch at index position '0'. More on this in the next section. See examples on Customizing branch label colors below

Customizing branch colors

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:

Here, you can see that branch8 and branch9 colors and the styles are being picked from branch at index position 0 (main) and 1(branch1) respectively, i.e., branch themeVariables are repeated cyclically.

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 Commit Label Font Size

You can customize commit using the commitLabelFontSize theme variables for changing in the font size of the commit label .

Example: Now let's override the default values for the commitLabelFontSize variable:

See how the commit label font size changed.

Customizing Tag Label Font Size

You can customize commit using the tagLabelFontSize theme variables for changing in the font size of the tag label .

Example: Now let's override the default values for the tagLabelFontSize variable:

See how the tag label font size changed.

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:

See how the highlighted commit color on the first branch is changed to the value specified in the theme variable gitInv0.