_95-potential_architectures.Rmdx

* APPENDIX E - Potential Docker Architectures

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
if (!require(DiagrammeR)) install.packages("DiagrammeR")
library(DiagrammeR)
```

## Small architecture
The simplest architecture we can possibly use has just one container, running PostgreSQL. 

* We talk to the PostgreSQL container for data analysis from RStudio on the host, using the `DBI` and `RPostgres` packages.
* We talk to the PostgreSQL container for administration by building `docker exec` commands and executing them with `system2`.
* We either mount the `Backups` volume on the host filesystem or we copy files to and from `Backups` with `docker cp` commands wrapped with `system2`.

```{r echo=FALSE}
small_widget <- DiagrammeR::mermaid("
graph LR
    Host_Filesystem---Backups
    RStudio---PostgreSQL
    subgraph Containers
    PostgreSQL
    end
    subgraph Volumes
    PostgreSQL---pgdata
    PostgreSQL---Backups
    end
end
")

# export the widget to an SVG file
small_widget %>% 
  DiagrammeRsvg::export_svg() %>% 
  cat(file = "diagrams/fkgraph.svg")

# convert to PDF and PNG - LaTeX doesn't read SVGs by default
magick::image_read("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.pdf", 
    format = "pdf"
  )
magick::image_read_svg("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.png", 
    format = "png"
  )
```

```{r echo=FALSE}
# display the PNG/PDF - this works in both HTML and PDF
knitr::include_graphics("diagrams/fkgraph.png", auto_pdf = TRUE)
```


<br><br><br>

## Medium architecture
The medium architecture adds a `pgAdmin4` container for administering the PostgreSQL server. We have the same workflow for backups, and we still do the data analysis with host RStudio, but we manage the server with a browser pointed at the `pgAdmin4` web service.

```{r echo=FALSE}
medium_widget <- DiagrammeR::mermaid("
graph LR
    Host_Filesystem---Backups
    RStudio---PostgreSQL
    Browser---pgAdmin4
    subgraph Containers
    PostgreSQL---pgAdmin4
    end
    subgraph Volumes
    pgAdmin4---Backups
    PostgreSQL---pgdata
    end
end
")

# export the widget to an SVG file
medium_widget %>% 
  DiagrammeRsvg::export_svg() %>% 
  cat(file = "diagrams/fkgraph.svg")

# convert to PDF and PNG - LaTeX doesn't read SVGs by default
magick::image_read("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.pdf", 
    format = "pdf"
  )
magick::image_read_svg("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.png", 
    format = "png"
  )
```

```{r echo=FALSE}
# display the PNG/PDF - this works in both HTML and PDF
knitr::include_graphics("diagrams/fkgraph.png", auto_pdf = TRUE)
```

<br><br><br>

## Large architecture (95)
In the large architecture, we add a `rocker/rstudio` container, thus creating a fully-containerized workflow. We talk to the containers via a browser only.

```{r echo=FALSE}
large_widget <- DiagrammeR::mermaid("
graph LR
    Host_Filesystem---Backups
    Browser---Rocker_RStudio
    Browser---pgAdmin4
    subgraph Containers
    PostgreSQL---pgAdmin4
    Rocker_RStudio---PostgreSQL
    end
    subgraph Volumes
    pgAdmin4---Backups
    PostgreSQL---pgdata
    end
end")
```


# export the widget to an SVG file
large_widget %>% 
  DiagrammeRsvg::export_svg() %>% 
  cat(file = "diagrams/fkgraph.svg")

# convert to PDF and PNG - LaTeX doesn't read SVGs by default
magick::image_read("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.pdf", 
    format = "pdf"
  )
magick::image_read_svg("diagrams/fkgraph.svg") %>%
  magick::image_write(
    path = "diagrams/fkgraph.png", 
    format = "png"
  )
```

```{r echo=FALSE}
# display the PNG/PDF - this works in both HTML and PDF
knitr::include_graphics("diagrams/fkgraph.png", auto_pdf = TRUE)
```


 -- M. Edward (Ed) Borasky
 -- M. Edward (Ed) Borasky