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.
NOTE: checkout
and switch
can be used interchangeably.
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 diagramREVERSE
: 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 IDtag
--> To add a custom tag to your merge committype
--> 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:
- 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 thecommit id:$value
format of declaring commits. See the examples from above. - The given commit must not exist on the current branch. The cherry-picked commit must always be a different branch than the current branch.
- Current branch must have at least one commit, before you can cherry-pick, otherwise it will cause an error is throw.
- 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.
- 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 istrue
. If set tofalse
, the branches are not shown in the diagram.showCommitLabel
: Boolean, default istrue
. If set tofalse
, the commit labels are not shown in the diagram.mainBranchName
: String, default ismain
. The name of the default/root branch.mainBranchOrder
: Position of the main branch in the list of branches. default is0
, meaning, by defaultmain
branch is the first in the order.parallelCommits
: Boolean, default isfalse
. If set totrue
, 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 from0
using themainBranchOrder
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 theirorder
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 test1
is 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 three graph orientations: Left-to-Right (default), Top-to-Bottom, and Bottom-to-Top.
You can set this with either LR:
(for Left-to-Right), TB:
(for Top-to-Bottom) or BT:
(for Bottom-to-Top) 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:
Bottom to Top (BT:
) (v11.0.0+)
In BT
(Bottom-to-Top) orientation, the commits run from bottom to top of the graph and branches are arranged side-by-side.
To orient the graph this way, you need to add BT:
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
.