Kroki provides a unified API with support for BlockDiag (BlockDiag, SeqDiag, ActDiag, NwDiag, PacketDiag, RackDiag), BPMN, Bytefield, C4 (with PlantUML), Ditaa, Erd, Excalidraw, GraphViz, Mermaid, Nomnoml, Pikchr, PlantUML, SvgBob, UMLet, Vega, Vega-Lite and WaveDrom… and more to come!
This section offers a basic tutorial for evaluating Kroki. More comprehensive installation instructions are in the Kroki documentation.
Kroki uses a simple algorithm (deflate + base64) to encode your diagram in the URL:
GET /plantuml/svg/SyfFKj2rKt3CoKnELR1Io4ZDoSa70000
You can also call Kroki with POST:
POST /
{
"diagram_source": "Bob -> Alice : hello",
"diagram_type": "plantuml",
"output_format": "svg"
}In this case, you don’t need to encode your diagram.
It’s also possible to send your diagram as plain text using the Content-Type header.
The output format will be specified using the Accept header and the diagram source will be sent as the request body:
POST /plantuml
Accept: image/svg+xml
Content-Type: text/plain
Bob -> Alice : helloYou can also define the output format in the URL if you don’t want to add an Accept header:
POST /plantuml/svg
Content-Type: text/plain
Bob -> Alice : helloThe same concept applies when sending the diagram as JSON:
POST /plantuml/svg
{
"diagram_source": "Bob -> Alice : hello"
}Kroki has a modular architecture:
- server
-
A Java web server (powered by Vert.x) that acts as a gateway. Kroki server is built using Maven.
- umlet
-
A tiny Java API on top of UMlet (mini) to generate diagrams.
- nomnoml
-
A Node.js CLI on top of the Nomnoml diagram library.
- vega
-
A Node.js CLI on top of the vega diagram library. Also supports Vega-Lite concise grammar.
- blockdiag
-
A companion web server written in Python (powered by Flask and Gunicorn) that provides BlockDiag, SeqDiag, ActDiag, NwDiag, PacketDiag and RackDiag diagrams libraries.
- mermaid
-
A companion web server written in JavaScript (powered by micro) that provides Mermaid diagram library.
- bpmn
-
A companion web server written in JavaScript (powered by micro) that provides bpmn-js diagram library.
- bytefield
-
A Node.js CLI on top of the bytefield-svg diagram library.
- wavedrom
-
A Node.js CLI on top of the wavedrom diagram library.
- excalidraw
-
A companion web server written in JavaScript (powered by micro) that provides Excalidraw.
The first step is to install the local dependencies in your local repository using make:
$ make installLocalDependencies
Then you can build the project using Maven:
$ make buildServer
Once the Docker images are built, you can run Kroki using docker:
$ docker run -d -p 8000:8000 yuzutech/kroki
If you want to use BlockDiag, ActDiag, NwDiag, SeqDiag, PacketDiag, RackDiag or Mermaid, then you will also need to start companion containers.
You can use docker-compose to run multiple containers:
version: "3"
services:
core:
image: yuzutech/kroki
environment:
- KROKI_BLOCKDIAG_HOST=blockdiag
- KROKI_MERMAID_HOST=mermaid
- KROKI_BPMN_HOST=bpmn
- KROKI_EXCALIDRAW_HOST=excalidraw
ports:
- "8000:8000"
blockdiag:
image: yuzutech/kroki-blockdiag
ports:
- "8001:8001"
mermaid:
image: yuzutech/kroki-mermaid
ports:
- "8002:8002"
bpmn:
image: yuzutech/kroki-bpmn
ports:
- "8003:8003"
excalidraw:
image: yuzutech/kroki-excalidraw
ports:
- "8004:8004"$ docker-compose up -d